NEUTRON-SCATTERING STUDY OF MAGNETIC EXCITATIONS IN OBLIQUE EASY-AXIS ANTIFERROMAGNET FETIO3
NEUTRON-SCATTERING STUDY OF MAGNETIC EXCITATIONS IN OBLIQUE EASY-AXIS ANTIFERROMAGNET FETIO3
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DOI：
10.1088/0022-3719/19/35/013
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发表时间：
1986-12-20
期刊：
影响因子：
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通讯作者：
TAKEI, H
中科院分区：
文献类型：
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作者：
KATO, H;YAMAGUCHI, Y;TAKEI, H
利用弹性和非弹性中子散射实验研究了各向异性反铁磁FeTiO 3的磁结构和磁激发。详细的结构分析表明，在4.3K时，每个Fe 2+离子的自旋方向与六方晶系c轴成（2.2 ± 0.2）度倾斜，同时保持所有自旋共线.倾斜角被认为是几乎不敏感的温度变化高达Neel温度TN = 57.35+或-0.05 K，这是从次晶格磁化强度数据的幂律拟合确定。结果表明，由于晶体电场的单离子各向异性是不足以解释的磁结构。激发光谱，另一方面，表现出复杂的行为，反映了倾斜的易轴基态，其中五个不同的分支的磁性起源被确认存在于12 K。根据唯象理论，其中的有效各向异性被假定为具有正交对称性，由于的双折射，四个观察到的分支可以很好地再现，通过识别它们作为非简并的声学和光学磁振子模式，包括与横向声学声子的杂化。
Elastic and inelastic neutron scattering experiments have been carried out to investigate magnetic structure and magnetic excitations in anisotropic antiferromagnet FeTiO 3. A detailed structure analysis shows that the spin direction of each Fe 2+ ion is oblique away from the hexagonal c axis by (2.2+ or-0.2) degrees at 4.3 K with keeping all spins collinear. The oblique angle is found to be almost insensitive to the temperature variation up to the Neel temperature T N= 57.35+ or-0.05 K, which was determined from the power law fitting of sublattice magnetisation data. It is shown that single ion anisotropy due to the crystalline electric field are inadequate to explain the magnetic structure. The excitation spectra, on the other hand, exhibit a complicated behaviour, reflecting the oblique easy-axis ground state, in which five distinct branches of magnetic origin are confirmed to exist at 12K. According to the phenomenological theory, in which the effective anisotropy is assumed to have an orthorhombic symmetry due to the obliqueness, four of the observed branches can be well reproduced by identifying them as non-degenerate acoustic and optical magnon modes including a hybridisation with a transverse acoustic phonon.